Vented closure



G. L. ROY

VENTED CLOSURE June 10, 1969 Filed June 24, 1968 I I l l I INVENTOR GERALD L ROY ATTORNEY 3,448,882 Patented June 10, 1969 3,448,882 VENTED CLOSURE Gerald L. Roy, Lancaster, Pa., assignor to Armstrong Cork Company, Lancaster, Pa., a corporation of Pennsylvania Filed June 24, 1968, Ser. No. 739,321 Int. Cl. B65d 51/16, 53/00 US. Cl. 215-56 3 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION Field of the invention The invention relates to new and useful improvements in a closure means for containers, and more particularly a closure means which will vent when the internal pressure developing in the container becomes excessive.

Description of the prior art Numerous venting structures are available for relieving the excess pressure buildup within a container. Patent No. 2,424,801 discloses one type of venting structure wherein the glassware neck is provided with a special configuration which will permit gas to escape after the gas buildup has reached a point where it will lift the liner off the neck of the glasswjare. I

Patent No. 3,114,467 discloses another type of selfventing bottle cap wherein the bottle cap is provided with a special structurejiwhich permits the liner to rise up under the action of the liuildup of gas pressure. The raising of the liner away from the neck of the glassware then permits the gas to escape.

These abovestructures and all other structures currently available on the open market suffer from one major deficiency. While the structures will permit gas to escape, they are also equally suitable for permitting liquid to escape. Turning of the bottle upside down will permit the liquid to act on the venting structure and escape in the same manner as the gas would escape. This limitation makes the product very difiicult to handle from a packing and shipping point of view since the container must always be maintained in its upright position or else there will be leakage.

The primary object of the structure herein is to provide a structure which will permit the passage of gas, but prevent the passage of liquid.

Summary of the invention In the forming of conventional closures with liners, the liner is usually formed of a pulpboard material fastened to the inside of the closure and having a thin disc of any suitable facing material disposed over the pulpboard material to protect it against deterioration by the contents of the container and contamination of the contents of the container by the liner material. The facing material is completely impervious to liquid and gas.

It is proposed to use in a closure the same type of pulpboard lining material, but to replace entirely or in part the conventional impervious facing material with a fibrous, nonwoven, semi-permeable, polytetrafiuoroethylene sheet. This polytetrafluoroethylene sheet will be of the same relative thickness as the conventional facing material. This new facing material is semi-permeable in that it will permit the passage under normal circumstances of gas, but will prevent the passage of liquid. The normal pulpboard backing material normally will permit the passage of gas; and, consequently, excess pressure due to gas is relieved by the gas passing through the facing material, the lining material and out around the threads of the closure to the atmosphere.

Brief description of the drawing Description of the preferred embodiment The neck 2 of a conventional container has a substantially flat upper surface 4 against which the liner presses to form the liquid-tight seal. Threads 6 on the container engage with threads 8 of a conventional closure 10. The closure has a liner 12 which is composed of a lining material 14 and facing 16. The closure 10 and liner material 14 are conventional in the art as shown in Patent No. 2,359,924.

The difference over the prior art is that the facing material 16 is not the conventional nonporous sheet material. It is proposed to use a fibrous, nonwoven, semipermeable polytetrafluoroethylene as the facing material. An example of a polytetrafluoroethylene available for use is the material sol-d under the trade name Zitex by Chemplast, Inc. "Zitex is a nonwoven, fibrous, polytetrafluoroethylene membrane which has the ability under normal operating conditions to permit the passage of gas, but to prevent the passage of liquid. As such it functions as a semi-permeable membrane.

One specific example which has been found to be extremely effective in use with bleach containing bottles to permit the passage of gas, but to prevent the liquid bleach from escaping or attacking the pulpboard lining material is the Zitex membrane sold as No. E610-122D. This particular membrane has a maximum porous size of 10 to 20 microns and comes in a thickness of 2.8 mils. This material is used as a facing for the conventional pulpboard lining material and both the lining material and the facing are used with a conventional screw-type closure for a conventional bleach bottle. Tests have shown that this particular structure readily vents the buildup of internal pressures within the bleach bottle, but the semi-permeable membrane prevents the bleach from leaking past the facing when the bleach bottle is upside down. This thus prevents the bleach from attaching the pulpboard lining material or working its way past the liner to drip down the outside surface of the bottle and attack the bottle label, the packaging case carrying the bottle or the shelf supporting the bottle in the store.

Other types of fluorocarbons may also be used as long as they possess the property of semi-permeability. Also other membranes of a different pore size and thickness may be used depending upon the type of liquids contained within the container and the liquid pressure developed on the surface of the facing material.

What is claimed is:

1. A self-venting closure cap for a container having a threaded neck portion presenting a circular rim, said cap including a cap body having a crown portion and a depending internally threaded skirt designed for threaded engagement with the threaded neck portion of the containep, the inside face of the crown portion of the cap receiving a liner composed of a pulpboard lining ma- 3- The self-venting closure cap of claim 2 wherein the terial at least partly faced with a fibrous, semi-permeable, cap is used in combination with a container containing polytetrafiuoroethylene sheet material which constitutes a bleachmeans for venting the internal gas pressure :buildup with- References Cited in the container while at the same time preventing the 5 UNITED STATES PATENTS passage of liquid past the facing material. 07 27 1/1963 P6116 et 215 56 2. The self-venting closure cap of claim 1 wherein the 3,315,831 4/ 1967 Scott 215. 5

fibrous polytetrafluoroethylene sheet is a nonwoven fiber forming a multiplicity of pores having a size of 5 to 20 GEORGE HALL Pnmary Exammer microns and the sheet is of a thickness of approximately 10 U5 C1, X R,

milS- 2l540; 22044 

